Cobalt-doped tin disulfide catalysts for high-capacity lithium–air batteries with high lifetime

Abstract

Dual electrolyte lithium–air batteries have received widespread attention for their ultra-high energy density. However, the low internal redox efficiency of these batteries results in a relatively short operating life. SnS₂ is widely used in Li–S batteries, Li-ion batteries, photocatalysis, and other fields due to the high discharge capacity in batteries. However, SnS₂ suffers from low electrical conductivity and slow redox kinetics. In this study, Co-doped SnS₂ is prepared by hydrothermal method for application in dual-electrolyte lithium–air batteries to study its electrochemical performance and its catalytic reaction process by DFT theory. Conductivity tests show that the Co doping enhances the electrical conductivity of the material and high transmission electron microscopy (HRTEM) results demonstrate that the Co doping of SnS₂ increases the grain plane spacing and the material indicates that defects are created on the surface of the material, which is more beneficial to the electrochemical performance of the cell. Co-doped SnS₂ exhibits excellent good cycling stability and high discharge capacity in a dual electrolyte lithium–air battery, maintaining a 0.7 V overpotential for 120 h at a current density of 0.1 mA cm⁻², with a cell life of over 500 h and an initial discharge capacity showing excellent results up to 16 065 mA h g⁻¹. In addition, this study explores the catalytic activity of Co-doped SnS₂ based on density flooding theory (DFT). The results show that Co atoms have a synergistic effect with Sn atoms to perturb the lattice parameters. The calculations show that the catalytic activity is enhanced with the increasing of Co doping content and 3Co–Sn exhibits minimal overpotential.